L.A.R. Grizzly .357/.45 GWM

I hope someone can help me to clarify something…

I have an L.A.R. Grizzly .45 WinMag. (That I am about to sell) A few years ago I was in the marked for a few extra mags for my gun and contacted a supplier in Sweden. He had mags, but they were in kits with a few parts and a barrel. I bought two kits. With one of the kits there was a caliber that I can find very little info about on the net. It is .357/.45 GWM. Now that I am about to sell the gun, I want to find out if this is a collector’s item? And if so is there any value to it?